Apparatus for drying fabrics



March 17, 1964 H. E. PECK APPARATUS FOR DRYING FABRICS 2 Sheets-Sheet 1 Filed July 27, 1960 IN VEN TOR.

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HENRY E. PECK lllllll on m [Illlllllllllllllll IIIIIL Qm March 17, 1964 c 3,125,424

APPARATUS FOR DRYING FABRICS Filed July 27, 1960 2 Sheets-Sheet 2 FIG. 2

INVENTOR.

HENRY E. PECK United States Patent 3,125,424 APPARATUS FOR DRYING FABRECS Henry E. Peck, Fairport, N.Y., assignor to Trieot Equipm rit Company, Incorporated, Fairport, NAG, a corporation of New York Filed July 27, 1960, Ser. No. 45,582 5 Claims. (Cl. 34-155) The present invention relates to a method and to apparatus for drying fabrics, and more particularly to a method and apparatus for pro-drying synthetic fabrics, such as rayon, nylon, Orlon etc., after they have been dyed, to reduce their moisture content before delivery to the final drier. In a still more specific aspect the invention relates to a process and apparatus for pre-drying dyed tricot fabrics to reduce their moisture content in order to speed up and minimize the cost of final drying.

In conventional methods of drying fabrics, after the completion of a dyeing operation, a vacuum extractor may be used to extract excess moisture or the fabric may be transported to a centrifuge to extract the excess moisture. Then the fabric is secured to a tenter frame which feeds it to and through a drier.

The amount of air or drying gas that can be forced or pulled through the fabric, even when pinned or clamped to a tenter frame, is limited, however, by the limited porosity of the fabric since the force of the drying atmosphere against the suspended web will billow it and distort it. This is particularly the case because the porosity of the fabric is further reduced by swelling of the fibers or threads due to their high moisture content. This governs and limits the rate of drying and the degree of wetness that can be handled in a drier.

Furthermore, if the moisture content of the incoming fabric varies appreciably, the control of a tentering drier is difiicult, especially where high temperatures are used in order to stabilize and set the dye in the fabric, when it is necessary to bring the fabric to within a few percent of complete dryness.

One object of the present invention is to provide a method and apparatus for reducing the moisture content of fabric to a uniform level after it leaves the dye vessel, and prior to its being attached to a tenter frame, so that the tenter frame drier is able accurately further to reduce the moisture content of the fabric to within a few percent of complete dryness.

Another object of this invention is to provide a method and apparatus of the character described which permits the force of the drying gas in the tenter frame drier to be substantially reduced without adversely affecting the rate of drying, thereby to prevent billowing and distortion of the fabric in the tenter frame drier.

A further object of this invention is to provide predrying apparatus of the character described which can effectively handle fabrics of different widths including fabrics of substantially narrower widths than the maximum width that the apparatus can accommodate.

A further object of this invention is to provide a method and apparatus of the character described which does not stretch or distort the fabric prior to its being attached to the tenter frame.

Other objects of the invention will become apparent from the accompanying drawings, the specification and the appended claims.

In the drawings:

FIG. 1 is a fragmentary side elevation of a fabric predrier cofihtructed according to one embodiment of this invention, parts being broken away, and a length of fabric being shown en route from a pad or a dye vessel through the pro-drier to the tentering drier, the means for supporting the fabric on the journey to the tentering drier being shown also;

FIG. 2 is a fragmentary sectional view of the pre-drier taken on line 2-2 of FIG. 1 and looking in the direction of the arrows; and

FIG. 3 is a fragmentary sectional view, taken on line 33 of FIG. 2 looking in the direction of the arrows, and showing on an enlarged scale the conveying and supporting portion of the pre-drier.

In the pre-drier of the present invention, the fabric is supported on a moving screen, which can be made of bronze wire, plastic, etc. and which, in turn, is supported on a porous bed over which the screen can slide with a minimum of friction. As the screen, which may be in the form of an endless belt, carries the fabric through the predrier, a large volume of warm air is pulled down through the fabric to reduce its moisture content, which may be or more on a dry basis as it leaves the pad or dye vessel, to say 30% to 50%. The fans, which pull the air down through the fabric, may be located under the bed or at a distance from the bed. A heat exchanger above the bed heats the air to a high enough temperature to accomplish the drying. The bed, over which the screen travels, is made up of porous fine-weave material, such as corduroy cloth type stainless steel filter screen, having a resistance to air flow at the velocities employed (under 1000 ft./min.), of about ten times the resistance of the fabric alone (2 to 5 inches versus /4 to /2 inch). Since the fabric accounts for only 10% of the air resistance, the tendency of the air to bypass through the portions of the screen, which are not covered by fabric, is very slight. This permits the pre-drier to be used effectively in pre-drying various width of fabric, even fabrics which are of substantially less width than the screen.

Preferably, the wet fabric, after it is removed from the dye vessel, is first caused to travel over a spreader roller which smooths out any wrinkles in the fabric, and then through a pair of rollers to uncurl its edges before it is laid on the moving screen which carries the fabric through the pro-drier. The moisture content of the fabric is preferably measured as it leaves the pre-drier by a conventional moisture-measuring device which controls the opening of dampers in the exhaust conduits of the fans, or the temperature of the drying atmosphere, thereby to control the rate of drying. In this way the fabric leaves the pre-drier with a uniform moisture content which may be around 30%.

After the fabric leaves the pro-drier it is attached to a tenter frame in conventional manner and is carried through the tenter frame drier. Since the moisture content has now been materially reduced and is uniform for the length of fabric, there is much less resistance in the tenter frame drier to the flow of the drying atmosphere through the pores of the fabric, and the velocity of the drying atmosphere, that is necessary to effect the proper final drying, may be substantially reduced, all of which prevents distortion of the fabric on the tenter frame and insures uniform drying results.

Referring now to the drawings by numerals of reference, iii denotes generally the pre-drier. It is generally rectangular in transverse cross-section, and has a front wall 12, a rear wall 14, and a top wall 16, a bottom wal it, and side walls 25) and 22. (FIG. 2). These walls bound the pre-drying chamber.

The front wall 12 has an elongate horizontal slot 24 through it which extends substantially the full width of the wall 12 between the side walls 2% and 22. The rear wall 14 also has a similar elongate horizontal slot it: in it that is at substantially the same elevation and is of substantially the same width as the slot 24. The fabric, which is to be pre-dried, enters the pro-drying chamber through slot 24, and leaves the chamber through slot 26.

An arched support or plate 28, which is perforated and may be made of expanded metal, for example, is mounted in the pre-drying chamber just below the slots 24 and 26 to bridge the space between the front and rear walls 12 and 14 of the chamber. The front edge of this plate 28 is securely attached to the front wall 12 below and adjacent the bottom of the slot 24; while the rear edge of the plate 28 is securely attached to the re6ar wall 14 below and adjacent the bottom of the slot 2 The plate 28 supports a sheet of porous, fine-weave metallic cloth 30, such as corduroy cloth type filter screen, which is preferably made of stainless steel, and which provides a high resistance to air flowing through it. This sheet 30 rests directly on the plate 28 and engages tightly at its edges against the walls 12, 14, 20 and 22.

Mounted on the front wall 12 below the slot 24 and outside the chamber is an elongate roller 32 which is rotatably supported at opposite ends by brackets 34. Mounted on the rear wall 14 below the slot 26 and outside the chamber is an elongate roller 36 which is rotatably supported at opposite ends in brackets 38. Mounted to travel over the rollers 32 and 36 is a flexible screen 46 which may be made, for instance of bronze wire, or even plastic. This screen 40 is in the form of an endless belt, the upper reach of which enters and leaves the pre-drying chamber through the two slots 24 and 26, respectively, and the lower reach of which enters and leaves the chamber through two other horizontal slots 42 formed in the front and rear walls 12 and 14, respectively. Slots 42 are parallel to and below slots 24 and 26, respectively. Screen 48 is driven by roller 36. There is a pulley 44 secured to roller 36 that is driven from motor 48 by a chain or V-belt 46. The upper reach of the screen 49 is mounted to slide over the bed or screen 30 as the screen 40 travels through the pre-drying chamber.

Mounted in the pre-drying chamber adjacent its top wall 16 is an air filter 50, and mounted below the air filter 50 and above the endless screen 40 is a fin-type heat exchanger 52 for heating the air in the chamber to approximately 150 F. The hot moisture-laden atmosphere from the tentering drier, for example, may be drawn through the heat exchanger 52 by a suction blower 54. This moisture-laden atmosphere flows to the heat exchanger from the tentering drier through a duct 56 and pipes 58, and leaves the heat exchanger 52 through a manifold 60 and pipes 62. The condensate from the heat exchanger flows off through a pipe 64 and a trap 66. The suction blower 54 extracts the non-condensables; and the vapor exhausts through a pipe 68.

Mounted in the pre-drying chamber below the lower reach of the screen 40 are a pair of suction fan units generally designated at 70. These fan units 70 comprise casings 72 in which fan blades 74 are mounted to be driven by motors 76. The fan casings 72 are apertured at their tops so that as the fan blades revolve, air is drawn down through the top Walls of the casings and exhausted out through ducts 78 which open outside the chamber. Adjustable dampers 80 are positioned in the ducts 78 for controlling the rate of air flow.

Attached to the front wall 12 of the chamber 10 is a bracket 82, on which are mounted trunnion supports 84 between which an elongate spreader roll 86 is rotatably mounted. The fabric 88, which is to be pre-dried, travels from the dye vessel over this spreader roll to the predrying chamber. This spreader roll 86 has helical ridges 90 (FIG. 2) around its periphery; and these ridges are of opposite hands at opposite sides of the longitudinal center of the roll. The ridges act to spread out the fabric 88 to remove any wrinkles therein before the wet fabric enters the pro-drying chamber.

To further assist in straightening out the fabric and removing the wrinklers, decurling rollers 92 are provided at opposite side edges of the fabric. These rollers 92 are arranged in pairs, one roller of a pair engaging the upper side of the fabric and the other roller of the pair engaging the underside of the fabric. These rollers are idlers and may be supported from bracket 82 in any suitable manner between spreader roll 36 and roller 32.

The rollers 86 and 92 insure that the fabric 88 is spread out fiat on the endless screen 40 as the screen carries the fabric into the pre-drying chamber. The large area of contact of the fabric 88 with the screen 4i and the frictional resistance between the wet fabric 88 and the screen 40 causes the screen to carry the fabric without any distortion or stretching.

A plurality of rollers 94 guide the cloth after it leaves the pre-drying chamber so that the cloth may be hooked to a conventional tenter frame which carries the fabric to the tentering drier. A platform 101 is provided adjacent the tenter frame 96 so that the operator can control the attaching of the fabric to the tenter frame, examine the fabric for any possible defects and Watch over the drying operation.

A conventional moisture-content measuring device 98 senses the moisture content of the fabric as it leaves the pre-drying chamber. This measuring device is connected to conventional controllers shown diagrammatically at 100 (FIG. 2) which adjust the dampers to increase or decrease the fiow of air through the fabric. The measuring device might, however, be connected to temperature controls to vary the temperature of the drying air pulled through the pre-drying chamber. The measuring device 98 and controllers maintain a selected moisture content of the fabric, say at approximately 30% on a dry basis. This makes possible more efficient operation of the tentering drier. It is to be noted that even without the automatic control of the dampers 80, the moisture content of the fabric as it leaves the pre-drying chamber is more uniform and constant that it would be were no predrier provided. Therefore, even if the moisture-content measuring device and damper controls were not employed, the pre-drier would improve the efficiency of operation of the final tentering drier.

As already stated, the bed 30 is made up of porous, fine-weave material having a resistance to air flow at the velocities employed of about ten times the air resistance of the fabric 88 alone. Since the fabric accounts for only 10% of the air resistance, the tendency of heated air in the pre-drier drawn down by fans 70 to bypass through the portions of the bed 30, which are not covered by fabric 88, is very slight. Thus, the pre-drier can be used efficiently for pre-drying different widths of fabric.

The bed can be made of 20 x 300 mesh stainless steel wire. The conveyor can be made of 80 mesh Phosphor bronze wire cloth. This will slide easily on the steel wire bed; and the wet fabric will adhere to the Phosphor bronze wire cloth by frictional engagement so that it is carried along by the conveyor without pull on the fabric.

While the invention has been described in connection with a specific embodiment thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. Apparatus for drying fabric comprising an enclosed heating chamber having an entry port at one end and an exit port at its opposite end, a perforate support of low resistance to passage of air therethrough, a bed of slippery porous material resting on said support and extending transversely of said chamber, said material offering a higher resistance to air flow therethrough than the fabric, a porous endless conveyor for conveying the fabric through said chamber from its entry port through its exit port, said conveyor carrying the fabric on the upper face of its upper reach and being mounted to pass through said ports and having the under face of its upper reach slidable on said bed, said conveyor being more porous than said bed, means for moving said conveyor, and means for drawing air through the fabric, said upper reach of said conveyor, and said bed successively as said conveyor carries the fabric through said chamber, said bed having its marginal edges tightly engaging the walls of said chamber so that air moving from above said bed to below said bed must pass through said bed.

2. Apparatus for drying fabric as claimed in claim 1, wherein said bed has a resistance to air flow of approximately ten times the resistance of the fabric alone.

3. Apparatus for drying fabric as claimed in claim 1 wherein said bed is made of porous, fine-mesh metallic wire screening, and said conveyor is made of a coarser mesh wire cloth which will slide easily on said bed.

References Cited in the file of this patent UNITED STATES PATENTS 849,141 Ladd Apr, 2, 1907 1,722,655 Bone July 30, 1929 1,728,471 Bratring Sept. 17, 1929 1,741,266 Witham Dec. 31, 1929 2,050,625 Orr Aug. 11, 1936 2,300,982 Slagboom et a1. Nov. 3, 1942 2,731,732 Harris et al Jan. 24, 1956 2,758,388 Westerberg Aug. 14, 1956 

1. APPARATUS FOR DRYING FABRIC COMPRISING AN ENCLOSED HEATING CHAMBER HAVING AN ENTRY PORT AT ONE END AND AN EXIT PORT AT ITS OPPOSITE END, A PERFORATE SUPPORT OF LOW RESISTANCE TO PASSAGE OF AIR THERETHROUGH, A BED OF SLIPPERY POROUS MATERIAL RESTING ON SAID SUPPORT AND EXTENDING TRANSVERSELY OF SAID CHAMBER, SAID MATERIAL OFFERING A HIGHER RESISTANCE TO AIR FLOW THERETHROUGH THAN THE FABRIC, A POROUS ENDLESS CONVEYOR FOR CONVEYING THE FABRIC THROUGH SAID CHAMBER FROM ITS ENTRY PORT THROUGH ITS EXIT PORT, SAID CONVEYOR CARRYING THE FABRIC ON THE UPPER FACE OF ITS SUPPER REACH AND BEING MOUNTED TO PASS THROUGH SAID PORTS AND HAVING THE UNDER FACE OF ITS UPPER REACH SLIDABLE ON SAID BED, SAID CONVEYOR BEING MORE POROUS THAN SAID BED, MEANS FOR MOVING SAID CONVEYOR, AND MEANS FOR DRAWING AIR THROUGH THE FABRIC, SAID UPPER REACH OF SAID CONVEYOR, AND SAID BED SUCCESSIVELY AS SAID CONVEYOR CARRIES THE FABRIC THROUGH SAID CHAMBER, SAID BED HAVING IS MARGINAL EDGES TIGHTLY ENGAGING THE WALLS OF SAID CHAMBER SO THAT AIR MOVING FROM ABOVE SAID BED TO BELOW SAID BED MUST PASS THROUGH SAID BED. 